PENSACOLA, Fla. (AP) — Crucial pieces of a lawsuit challenging the Obama administration's health care overhaul can go to trial, with a judge ruling Thursday he wants to hear more arguments over whether it's constitutional to force citizens to buy health insurance.

In a written ruling, U.S. District Judge Roger Vinson said it also needs to be decided whether it's constitutional to penalize people who do not buy insurance with taxes and to require states to expand their Medicaid programs. Another federal judge in Michigan threw out a similar lawsuit last week.

Vinson set a hearing for Dec. 16. The lawsuits will likely wind up before the U.S. Supreme Court.

In his 65-page ruling, Vinson largely agreed with the 20 states and the National Federation of Independent Business, saying Congress was intentionally unclear when it created penalties in the legislation. The states have argued that Congress is overstepping its constitutional authority by penalizing people for not doing something — not buying health insurance.

The penalties for those who do not buy insurance are never referred to as taxes in the 2,700-page act, Vinson wrote. Attorneys for the Obama administration argued at a September hearing that the penalties should be considered a tax levied by Congress — as allowed by its constitutional power to regulate interstate commerce.

"One could reasonably infer that Congress proceeded as it did specifically because it did not want the penalty to be 'scrutinized' as a $4 billion annual tax increase," Vinson wrote.

"It seems likely that the members of congress merely called it a penalty and did not describe it as revenue-generating to try and insulate themselves from the potential electoral ramifications of their votes."